The invention relates to a sensor for measuring the surface of an object, having a contrasting unit for projecting a pattern onto the surface of the object, and having a camera for recording the pattern projected onto the surface of the object. This sensor, with an evaluation unit that can be connected to the sensor or integrated with the sensor, is especially suitable for the measurement principle of triangulation.
Such sensors operating on the principle of triangulation are already known. They use lasers as a contrasting unit, and for contrast purposes they project a stripe onto the surface to be measured. This fundamental principle is known for instance from U.S. Pat. No. 6,256,099 B1 or from German Patent Disclosure DE 44 02 414 A1. By evaluating the stripe recorded by the camera, 3-dimensional points can be ascertained along a curve, which provide information about the surface structure. A disadvantage of the previously known sensors is that because of the laser for generating the contrast stripe, they have a large structural shape. Moreover, the laser light presents safety risks to humans located in the measurement region, if the laser light strikes the retina. Moreover, lasers are sensitive optical devices, so that the known sensors react sensitively to jarring and taken all in all are not robust.
From German Utility Model DE 298 16 344 U1, a similar device for contactless optical 3-dimensional measurement analysis is known, in which a projector, embodied for instance as an LED lighting fixture, and a camera are provided in a sensor housing. While the projector is located transversely to the emission direction and the projection image is deflected from the housing via a mirror, the camera is located with its optical axis in the emission direction. This makes for a tall sensor housing, which can easily collide with the vehicle to which it is affixed, or restricts the adjustment path thereof.
From German Patent Disclosure DE 197 42 264 A1, an endoscope for optical 3-dimensional detection of objects is known, having a recording device and a surface lighting fixture, embodied as a projector, which is located along the longitudinal axis of the endoscope housing. The projection image and the recorded image exit and enter the endoscope through a common opening. As a result, a compact measurement system is created that enables 3-dimensional detection of an object even at inaccessible locations. In published US Patent Disclosure US 2001/0038705 A1, a similar optical principle is described for a scanning system, in which a projected image and a recorded image exit and enter through a common opening. Because of this optical arrangement, however, precise measurement of the object is not possible.